Basically there are few questions i want to ask :
1) For the transmitter circuit set the frequency to 5kHz?
2) Is the capacitor (100uf) before the speaker is necessary?
3)Is the capacitor (0.01uf) for the NE555 timer's pin5 is necessary?
4) Does resistor is necessary to place before the collector of the phototransistor to prevent damage?
Problems after i connected the circuit :
1) The led is keeps turned 'ON' no matter what. Isnt it suppose to turn off when both ir emitter and phototransistor is facing together? Even i changed the reset pin to ground to reset the circuit. After that, i realized the NPN transistor and phototransistor is damaged i don't know why. The circuit connection seems no problem at all .
I brought the ir emitter and phototransistor is both 940nm from KINGBRIGHT The picture is not very clear and sorry for my english haha